As of this moment, I can't say if there is any best altcoin in which the market is still in down situation. As we all know the market is so high way back January 2018, but we didn't expect that it will down tremendously. Well, I still believe that it will recover soon especially that we already almost reach the last quarter of this year, hoping that we have a great and good market as well as the ethereum.
For me it's reliable to buy ethereum so this is they only one I trusted in altcoin due to its demand by people and there prices fluctuates anytime. I believe it will grow more in the end of year 2018 so I'm now collecting more coins in ETH for hodling it.